Why do mosquitoes bite some people more than others?

There are lots of theories about why mosquitoes attack some people whilst leaving others alone. Larger persons who emit more CO2, beer-drinkers, and sweatier people have all come under scrutiny as supposedly more attractive to these bugs. We now know one thing for sure — that genetics and an individual’s body chemistry are the keys to understanding this fatal attraction. Statistically, only about one in ten people are particularly attractive to mosquitoes.

Why do mosquitoes attack some people and not others?

Lets look at what mosquitoes are looking for when they crash land on our skin. Without any hint of sexism we can say that only female mosquitoes will bite, as they need mammal blood to feed their eggs. There are 150 species in the USA alone, and they all have preferences for their ideal blood fix. Experiments have proven this; scientists have tested the preferences of various mosquito species and got varying results.

Mosquitoes are choosy and they want the best for their eggs. We produce chemicals and microbes which make up our unique body odour. They know exactly the right chemical mix and its odour because this accurately represents the blood they want. They can also detect these attractive aromas up to 30 metres away!

What makes up this chemical mix? Just think that we have 100 trillion microbes, which is ten times the number of human cells we possess. We have a unique microbial signature, which is mostly due to genetics. This will determine what type of bacteria we host in our gut and bodies. These microbes are an essential part of our immune system, so washing frequently is not going to do any good. It will certainly not deter the mosquitoes zooming in because their sense of smell is extremely sharp.

Your blood type is another factor

The mosquito is after blood, and if it smells right, you are going to be a target. In one limited experiment, it was found that mosquitoes preferred people with Type O blood twice as much as those with Type A. It is fascinating to know that in 85% of cases, you actually send a chemical signal indicating which blood type you have, which entices the mosquito.

So what makes a delicious cocktail for a mosquito?

More sweat and carbon dioxide have been cited, but the results from experiments are not always consistent. This is due mainly to the many different species and the enormously complex odour-making mechanisms each of us possesses.

Lactic acid seems to be a definite attraction to most mosquito species. When you eat certain foods, such as cheese, soya, yogurt and pickled vegetables, and do vigorous exercise, you will have more lactic acid on your skin. That is very attractive to some mosquito species.

Don’t believe all those people who say they are never bitten! The fact is that many more people are bitten by mosquitoes than you would think. It is all due to the reaction; people react in different ways to the mosquito leaving saliva when sucking their blood. This depends on environmental and allergic reactions. Many more people are bitten, but because they have no symptoms they are convinced that they are not attractive to mosquitoes. If only they knew!

To sum up, genetics and our chemical/microbial mix determine whether we are going to be bitten by mosquitoes or not. There seems to be a link between these and a person’s blood type. The amount of CO2, garlic or alcohol we consume, or dark-coloured clothing, are all secondary factors, but may help in keeping mosquitoes at bay.

Practical ways to keep mosquitoes at bay

Taking a few simple precautions can help. Covering up most exposed parts of the skin is a definite advantage. You can make sure that you put herbs and plants in your garden or on your balcony which actually repel mosquitoes. Avoid going out when humidity is at its peak (at dawn and dusk). This is also the time when winds die down, which give mosquitoes better ’landing conditions’. But even if you do all this, mosquitoes will still be attracted to you just as much!